Method for cleaning, sterilising and disinfecting dishes and other kitchen utensils and cleaning device

ABSTRACT

The invention relates to a method for cleaning, sterilising and disinfecting dishes and other kitchen utensils by means of a wash liquid ( 5 ). In order to permit an economically and technically advantageous cleaning, an electrical current is directly applied to an electrode ( 15, 16 ), arranged in the wash liquid ( 5 ) and embodied as a diamond and/or lead-tin electrode, to generate OH radicals ( 14 ) in said wash liquid ( 5 ), which permit cleaning, sterilising and disinfecting of dishes and other kitchen utensils. The invention also relates to a device for carrying out said method, wherein an electrolytic cell ( 20 ) with a pair of electrodes ( 15, 16 ), comprising a diamond electrode for generating OH radicals ( 14 ), is directly integrated into a wash water circuit of a dishwasher ( 1 ).

The invention relates to a method for cleaning, sterilising and disinfecting dishes and other kitchen utensils according to the generic definition of Claim 1 and a device for implementing the method.

STATE OF THE ART

Diverse forms of methods and devices for cleaning household objects, dishes or other kitchen appliances are already known. To attain a good degree of washing and cleanliness of items cleaned, their surfaces must be freed from soiling, bacteria or germs. This can be done in a relatively simple way, for example by washing with a household appliance or an electrically operated dishwasher. To this end, soiled dishes are placed in contact with a wash liquid in the dishwasher.

The soiled items or dishes are first placed in the dishwasher. Then, in particular tap water or household water and a detergent, in the form of a powder or a liquid, for example, are added. By means of a heating element, for example, the water or the wash liquid is brought to a required temperature, depending on the previously selected program, or the wash liquid or the water is mixed with the detergent. A chemical or physical dissolution process can then taken place in which, for example, the surface of the dishes cleaned is freed from soiling, bacteria and germs or these are transferred to the wash solution. After the actual wash operation, the surface of the dishes or kitchen appliances can be rinsed, for example with pure water. The wash or drying operation has ended after drying of the dishes or kitchen appliances thus treated or cleaned.

TASK OF THE INVENTION

The task of the invention is to provide a method or a device to make it possible to further improve cleaning of domestic items, dishes, etc. or other kitchen appliances or to advantageously enable them in relation to economic and technical aspects.

This task is resolved by Claims 1 and 11.

Expedient variants of the invention are pointed out in the dependent claims.

On the one hand, the invention is based on a method for cleaning, sterilising and disinfecting dishes and kitchen utensils by means of a wash liquid. One essential aspect of the invention lies in the fact that, by direct application of electrical current to an electrode arranged in the wash liquid that is embodied as a diamond and/or lead-tin electrode, OH radicals are generated in the wash liquid that enable cleaning, sterilisation and disinfection of the dishes and other kitchen utensils. This ensures effective and reliable cleaning or sterilisation and disinfection of dishes and kitchen utensils. In particular, high volumes of OH radicals can be generated with the method conforming to the invention or with the aid of the proposed electrodes. In particular, the OH radicals generated can make it possible to realise the cleaning method without detergents or without cleaning additives that were previously additionally required. It is especially advantageous that water or drinking water suffices as the wash liquid, out which OH radicals are generated with the proposed electrodes. OH radicals are distinguished, among other things, by their high activities and their ability to react or to oxidise in comparison with oxidising substances. Moreover, a cell-killing effect can be achieved with the OH radicals in relation to microorganisms, germs and bacteria.

It is also advantageous that electrical current, which is generally available anyway, is used for the method conforming to the invention. For the method, the electrical current is impressed directly on the electrodes within the dishwasher. The electrodes are preferably located in the circulating water and are in particular connected to a variable power supply unit. Thus, the electrodes can be placed in a comparably intensive contact with the wash liquid or the water pr water or, if applicable, further substances contained therein can wash around them. Any occurring hydrogen formation and the related ability to react with oxygen can be easily taken into consideration with known arrangements, e.g. by using semi-permeable diaphragms or a possible hazard potential can be reliably eliminated.

A further essential advantage of using diamond or lead-tin electrodes is that they do not entail any detrimental effect as can arise when using other electrode materials in aqueous systems. In the case of known electrodes, in particular those containing metal, for example consisting of platinum, portions or slight traces of these metals, for example atomic platinum or substances containing platinum can dissolve in the wash liquid or the surrounding water and can settle on the surface of the dishes and kitchen utensils. From there, platinum can be picked up by a person using the dishes through his or her food, thus reaching into the person's body. Platinum, however, in particular in comparatively low doses, is a substance that is hazardous to health or, in particular, a substance that poisons the cells. According to the invention, the detrimental use of platinum electrodes can be avoided.

It is also proposed to use a diamond and/or lead-tin anode. By the use of synthetically manufacturer diamond electrodes and/or lead-tin electrodes, for example, the extremely effective OH radicals can be generated during electrolysis, which particularly takes place on the anode. In principle, one or even several anode(s) made of the proposed substances can be provided for in the wash liquid.

The wash liquid is preferably mixed with agents for increasing electrical conductivity, in particular dishwashing detergent. To increase the electrical conductivity of the wash liquid or of the water washing around the electrodes, corresponding substances can be placed or dissolved in it. For example, a commercially available dishwashing detergent and/or an inorganic salt solution that is not decomposable can be used to increase electrical conductivity or as an electrolyte liquid. For example, Na₂SO_(4r) Na₃PO₄, NaCl, H₃B0₃ or a mixture of these salts can be used here. These substances or detergents are placed in dishwashers in particular via devices that ought to be well-known in themselves. Thus, for example, cleaning, sterilisation or disinfection of surfaces of the items to be cleaned can be enabled with commercially available wash solutions. On the one hand, the wash liquid or the wash solution serves as an electrolyte for applying electrical current to the solution and, on the other hand, it simultaneously serves as a wash solution for chemical dissolution of soiling or for electrochemical sterilisation, cleaning and disinfection of the surfaces of dishes. The generation of OH radicals on the anode or the possible simultaneous generation of the strong oxidation agents oxygen and/or ozone thus largely takes the place of possible additives for in particular chemical dissolution or removal of soiling by the wash solution.

It is particularly advantageous that a pulsating or continuous current is applied directly to the electrode arranged in the wash liquid. Thus, the necessary concentrations or volumes of OH radicals in the wash liquid can be reliably generated. In particular, pulsating application of current enables appreciably greater generation of OH radicals than when the current applied is not pulsating. Therefore, one quite essential point of the invention is to be seen in the fact that direct current is applied to the electrodes which is preferably impressed on the electrodes directly or in a pulsating fashion. As a result of the thus possible comparatively high OH radical generation rates or the thus achieved comparatively high OH radical concentrations in the wash liquid, wash times or times for a wash cycle can be shortened clearly in comparison with known processes or devices previously used. This is particularly attributable to the generation of highly efficient OH radicals on the anode or the simultaneous chemical and/or physical washing and sterilisation during the cleaning process. Pulsating current application can basically take place in accordance with one of different profiles that can be stipulated, for example in accordance with a wavy or sinusoidal, ramp-like or spiked profile as a function of time. An alternating current is preferably applied directly to the electrode arranged in the wash liquid. By means of an alternating application of current to the electrode, in which in particular the polarity alternates from plus to minus or the electrical polarity is reversed, particularly effective generation of OH radicals can be achieved.

It is also proposed to use a mixture of organic and/or inorganic wash solutions, such as commercially available detergents for cleaning, sterilisation and disinfection of dishes and other kitchen utensils. Additional positive effects during the cleaning process can be realised in this way. For example, surface-active or enzymatically active substances can clearly improve the cleaning effect. The process according to the invention is preferably to be used in combination with or with the use of commercially available detergents.

In a further preferred embodiment of the invention, dishes are cleaned by OH radicals and simultaneous chemical and physical removal of soiling.

In yet another preferred embodiment of the invention the wash liquid for cleaning, sterilising and disinfecting dishes and other kitchen utensils consists of a mixture of water and an inorganic salt such as Na₂SO₄ or sodium sulphate, Na₃PO₄ or sodium phosphate, NaCl or sodium chloride and/or H₃B0₃ or boric acid and/or a mixture of individual components. With these substances or, if applicable, a mixture of the individual components, particularly high cleaning performance can be achieved with the process conforming to the invention. Thus, the electrolyte solution can be provided as an alkaline aqueous wash solution or with conventional detergents or mixtures of the aforementioned salts.

It is particularly advantageous that the wash liquid for cleaning, sterilising and disinfecting dishes and other kitchen utensils is created out of a mixture of water and a commercially available detergent and/or one of the inorganic salts Na₂SO₄ or sodium sulphate, Na₃PO₄, or sodium phosphate, NaCl or sodium chloride and/or H₃B0₃ or boric acid, and/or a mixture of the individual components and/or a mixture of organic/inorganic aqueous solutions that is used as the electrolyte. The process according to the invention can be realised effectively and reliably with such an electrolyte.

It has proven particularly advantageous for the current density on the electrode to be set in amperes per unit of area specifically to the material to be cleaned, and for the current density to amount to between approx. 5 amperes per square decimetre (A/dm²) and approx. 300 amperes per square decimetre (A/dm²). A comparably high efficiency of the process according to the invention can be ascertained in the aforementioned current density range.

The invention is also based on a device to be able to implement the aforementioned process. One essential aspect lies in the fact that an electrolysis cell with an electrode pair encompassing a diamond electrode for generation of OH radicals is integrated directly in a wash water circuit of a dishwasher. In the thus formed device, the advantages already discussed above can be realised in a cleaning device or a dishwasher.

In a preferred embodiment of the device according to the invention, there is an electrically insulated spacer that prevents an electrical short-circuit between the anode and the cathode. Thus, the device according to the invention is able to meet the required safety standards when using electrical current in electrolysis cells. With an electrically insulated or insulating spacer on the corresponding zones of the electrolysis cell, negative influences due to an electric short-circuit in the energised state, in particular of the electrode pair, can be ruled out.

In the case of a further advantageous embodiment of the device according to the invention it is proposed for the electrolysis cell to be fed by the wash water sump by means of a circulation pump and for the dishes to be contacted via a spray arm. In this way, electrolyte or wash liquid collecting in the wash water sump can be compactly and reliably fed to the electrolysis cell with a comparatively robust circulation pump. Via the energised electrodes or the electrolysis cell, OH radical enrichment will then take place as described and then the wash liquid is brought into contact with the objects or dishes to be cleaned by means of the circulation pump via the spray arm or a correspondingly shaped brew device.

It is also proposed for an anode to arise out of a material that permits an overvoltage of the anode and thus OH radical generation. By means of a correspondingly designed anode or a corresponding anode material, in relation to an applied voltage on the anode a voltage can be achieved in such a way that OH radical generation is possible or a comparatively high rate of OH radical generation can be realised.

It is also proposed for the anode encompasses a synthetically manufactured diamond. All dimensions, shapes or compositions of the diamond electrode can be reproducibly manufactured with a synthetically manufactured diamond. For example, a synthetically manufactured diamond can be applied to titanium sheet or another suitable substrate material such as plastic.

Preferably, a diamond material, in particular a synthetic diamond material, can be doped with specific substances or compounds. For example, different metals can be incorporated in the synthetic diamond. In particular, a synthetic diamond doped with boron exhibits particularly advantageous properties in relation to an overvoltage of the anode thus formed. As a result of doping of the synthetic diamond, the diamond is made conductive or electrically conducting.

The special characteristic of the diamond electrode is also the form of water decomposition. While water is usually split during electrolysis into hydrogen (H₂) and oxygen (0₂), the diamond electrode supplies a certain operating range instead of oxygen the highly reactive or oxidative hydroxyl radical or OH radical and/or the intermediate or decomposition product ozone or 03.

Thus, for example, sterilisation of drinking water, for example, can be achieved. In particular, the chemical oxygen requirement value or the CSB value in sewage systems can be reduced. In these application areas, publications by the firms Waco, Condias and Gerus have been published in Germany. In them, the use of diamond electrodes is discussed exclusively for the sewage or drinking water industry.

It is also proposed for the anode consists of a platinum-coated electrode. A robust or electrochemically particularly resilient electrode can be provided in the form of a platinum-coated metal electrode. Besides the diamond electrode, which exhibits considerable stability in relation to aggressive and in particular alkaline, wash solutions, a platinum-coated metal electrode can in particular be used advantageously as the anode.

DESCRIPTION OF THE FIGURES

With reference to the figures, further characteristics and advantages of the invention are pointed out in the drawing.

In detail, the figures show:

FIG. 1 shows a highly schematic sectional view of a cleaning device with a device conforming to the invention and

FIG. 2 shows an enlarged partial view in a schematic depiction of a detail from FIG. 1.

FIG. 1 shows an in particular commercially available dishwasher 1 with an electrolysis device 2 corresponding to the invention. In FIG. 1, the electrolysis device 2 is presented merely schematically and in particular outside a housing 3 of the dishwasher 1. In principle, the electrolysis device 2 is in particular integrated directly in the dishwasher 1. The dishwasher 1, which is shown in the vertical section with individual components omitted comprises, in its bottom interior area, a wash sump 4 with wash electrolyte 5 gathered therein. The essential area in the interior of the dishwasher 1 is taken up by an accommodating device 6 for the items to be cleaned; for example the accommodating device 6 can consist of a dish rack 7. A spraying device 8, for example in the form of a spray arm, is provided for in the upper area of the dishwasher 1 for distribution or application of the wash electrolyte 5 onto the items (not shown) accommodated in the dish rack 7. To this end, the spray device 8 can, for example, comprise several spray nozzles 9 on a distribution strip 10. To circulate the wash electrolyte 5 or to transport it from the wash sump 4 to the spray device 8, a circulation pump 11 is integrated in a line 12. Besides the electrolysis device 2, the circulation pump 11 and the line 12 are also generally accommodated within the housing 3 of the dishwasher 1.

The arrangement shown in FIG. 1 also comprises an electrode pair 13 to generate OH radicals 14 which, to elucidate the subject matter, are indicated by dots. For generation of the OH radicals 14, for example electrical direct current is impressed via an electrical contact onto an anode 15 that comprises the electrical positive pole and a cathode 16 that comprises the electrical negative pole. During operation of the dishwasher 1 or during electrolysis, the wash water or the wash electrolyte 5 washes around the electrodes 15 and 16. Via electrical leads 17, the electrodes 15, 16 are connected to a variable rectifier 18. Thanks to the use in particular of the anode 15 as a synthetically manufactured diamond electrode, during electrolysis taking place in the electrolysis device 2 comparatively efficient OH radical generation is achieved on the anode 15. The wash electrolyte 5 can in particular comprise normal domestic water. Even with normal tap water, which already comprises a certain amount of conductivity, OH radical generation is basically possible. To lend the domestic water a higher electrical conductivity, commercially available dishwashing detergent for example or other salts which product ions in aqueous solution, for example, after dissolution, can be added via a filling funnel 19 on the top part of the dishwasher l into its interior. The wash electrolyte solution 5 thus obtained, which is electrically conductive or which comprises ions, is fed via the circulation pump 11 from the wash sump 4 to an electrolysis cell 20. There, the OH radicals are generated, in particular at the anode 15 when current is applied to the electrodes. By means of the OH radicals 15 that reach, for example, dishes in the dishwasher 1, via the line 12, the distribution strip 10 and the spray nozzles 9, chemical or physical dissolution of soiling can by means of the wash electrolyte solution 5 can take place completely or almost completely. The OH radicals 14 are transported via the wash electrolyte solution 5 by means of the line 12 from the electrolysis cell 20 in the flow direction to the spray nozzles and from there to the items to be cleaned. The spray device 8 or the spray nozzles 9 are shaped so that complete wetting or fine nozzling of the wash electrolyte solution 5 takes place, thus ensuring that the washing effect can evolve on the surfaces of the items to be cleaned. After the actual cleaning process, the wash electrolyte solution 5 with the cleaned off substances contained therein can be gathered by gravitational force in the wash sump 5 and, as described, mixed out of a protruding zone of the gathered wash electrolyte solution 5 once again with OH radicals 14 via the electrolysis device 2.

The electrolysis device from FIG. 1 is presented in greater detail in FIG. 2 in an enlarged and highly schematic form. According to the arrow P1, the wash electrolyte 5 passes through the line 12 by means of the circulation pump 11 to the electrolysis cell 20. The OHG radicals 14 are generated on the anode 15. In this process, the wash electrolyte 5 is also enriched with oxygen or ozone. These substances acting as oxidant carriers assist or accelerate the cleaning or washing process on the surfaces of the items or dishes to be cleaned. The direct current is generated by means of the variable rectifier 18 and brought into conductive contact via the supply cable or leads 17 with the anode 15 or the cathode 16. Electrically insulating spacers 21 are provided for electrical insulation of anode arms 15 a extending essentially vertically downwards from cathode arms 16 a extending upwards that are also alternately between them. The spacers 21 prevent in particular an electrical short-circuit during electrolysis between the anode arms 15 a and the cathode arms 16 a. With the OH radicals that reach the surface of the dishes to be cleaned, they can evolve their oxidising effect there.

With the proposed device or the process conforming to the invention it is in particular possible to save on commercially available detergents comprising tensides, phosphates or other additives, thus not only achieving saving effects, but also protecting resources or relieving the burden on the environment by reducing pollution of waste water from the cleaning device, or to realise a general energy saving thanks to shortened cleaning times.

List of Identification References:

-   1 Dishwasher -   2 Electrolysis device -   3 Housing -   4 Wash sump -   5 Wash electrolyte -   6 Accommodating device -   7 Dish rack -   8 Spray device -   9 Spray nozzle -   10 Distribution strip -   11 Circulation pump -   12 Line -   13 Electrode pair -   14 OH radicals -   15 Anode -   15 a Anode arm -   16 Cathode -   16 a Cathode arm -   17 Line -   18 Rectifier -   19 Filling funnel -   20 Electrolysis cell -   21 Spacer 

1-16. (canceled)
 17. A process for cleaning, sterilizing and disinfecting dishes and other kitchen utensils by means of a wash liquid wherein, by direct application of electrical current to a diamond and/or lead-tin electrode arranged in the wash liquid, OH radicals are generated in the wash liquid which radicals effect the cleaning, sterilization and disinfection of the dishes or other kitchen utensils.
 18. A process according to claim 17, wherein the electrode is an anode.
 19. A process according to claim 17, wherein the wash liquid is mixed with an agent for increasing electrical conductivity.
 20. A process according to claim 19, wherein the agent is a dishwashing detergent.
 21. A process according to claim 17, wherein a pulsating or continuous current is applied directly to the electrode arranged in the wash liquid.
 22. A process according to claim 17, where an alternating current is applied directly to the electrode arranged in the wash liquid.
 23. A process according to claim 17, wherein a mixture of organic and/or inorganic wash solutions is used for cleaning, sterilization and disinfection of the dishes and other kitchen utensils.
 24. A process according to claim 23, wherein the mixture is one of commercially available detergents.
 25. A process according to claim 17, wherein the dishes or other kitchen utensils are cleaned by OH radicals and simultaneous chemical and physical removal of soiling.
 26. A process according to claim 17, where the wash liquid consists of a mixture of water and an inorganic salt or a mixture of inorganic salts.
 27. A process according to claim 26, wherein the organic salt is sodium sulfate, sodium phosphate, sodium chloride or boric acid.
 28. A process according to claim 17, wherein the wash liquid is a mixture of water and a commercially available detergent and/or an inorganic salt and/or a mixture thereof and/or a mixture of organic/inorganic aqueous solutions used as an electrolyte.
 29. A process according to claim 28, wherein the inorganic salt is sodium sulfate, sodium phosphate, sodium chloride or boric acid.
 30. A process according to claim 17, wherein the current density on the electrode is set in amperes per area unit specific to the material to be cleaned and the current density is between about 5 A/dm² and about 300 A/dm².
 31. A device for cleaning, sterilizing and disinfecting dishes and other kitchen utensils by a liquid wash process, the device comprising an electrolysis cell that has an electrode pair having an anode and a cathode one of which is a diamond electrode for generating OH radicals and integrated directly in a wash water circuit.
 32. A device according to claim 31, further comprising an electrically insulated spacer that prevents an electrical short-circuit between the anode and the cathode.
 33. A device according to claim 31, further comprising a circulation pump for feeding the electrolysis cell from a wash water sump, and a spray arm for contacting the dishes and kitchen utensils to be cleaned, sterilized and disinfected.
 34. A device according to claim 31, wherein the anode is made of a material that that permits an overvoltage of the anode and thus the generation of OH radicals.
 35. A device according to claim 31, wherein the anode comprises a synthetically manufactured diamond.
 36. A device according to claim 31, wherein the anode comprises a platinum-coated metal electrode. 